In India, environmentalists are using ancient water conservation methods to tackle the country's growing water crisis.
Two years ago, a network of pipes was laid across rooftops of buildings in New Delhi's Jamia Hamdard University to divert rainwater to a storage facility on the campus grounds.
The system keeps the rainwater from simply flowing off pavements into the sewers. Instead, it percolates into the ground, replenishing the depleting groundwater reserves.
Ahmad Ali Khan, an engineer at the university, says water is now brimming in 12 wells that had been dying.
Mr. Khan says the rainwater has raised the ground water level by as much as six meters, and helped ease perennial water shortages on the campus.
The water-harvesting system at Jamia University is part of a campaign spearheaded by a public policy institute, the Center for Science and Environment, to revive an age-old tradition to ease India's crippling water shortages.
Sunita Narain, the center's director, says that historically, rainwater was never allowed to go waste in India, where in many regions it rains in short, sharp spells for less than one hundred hours a year. In earlier times, rain was captured in ponds, tanks and aquifers and kept for a dry day.
"Just think about it, one hectare of land, a hundred milliliters of rainfall gives you a million liters of water," she calculated. "Which means the challenge in India is when it rains, where it rains, you have to make sure you hold it and that really was the principle of the past…. That would mean re-creating rainwater harvesting in every house of India."
In cities, most of the rainwater gets into storm water drains. In rural areas it evaporates or flows into the sea because traditional water structures were mostly abandoned as people began relying on the government to provide water following India's independence more than five decades ago.
But efforts such as rainwater harvesting are again winning attention in a country where the government has never kept pace with demand from its steadily expanding population.
Some parts of the country are arid, others have ample rainfall or rivers. But the ever-rising demands of agriculture and crowded urban centers have depleted water sources at an alarming rate. Farmers have indiscriminately pumped groundwater to increase crops. Rivers and lakes are shrinking as they are harnessed to quench the thirst and sanitation needs of sprawling cities, but much of the sewage goes back untreated, polluting the country's water bodies, and reducing sources of fresh water.
As a result, in cities taps now run dry for much of the day. And in villages, women walk miles for a pot of water. Ghanasham Abhyankar at the World Bank says India's top priority is to ensure people have adequate drinking water.
"The main problem is they [water systems] are not available round the year, the quality of water is not necessarily good, the duration of supply is inadequate, the pressures are low, and if we have droughts, the situation becomes very difficult for the people," said Mr. Abhyankar.
Rakesh Behari, director of India's National Drinking Water Mission, says the government realizes it is not meeting public needs and is trying to involve communities more in financing and managing water systems to ensure a sustainable supply.
"We are gradually scaling up community involvement and they partially share the capital cost of water supply systems," he said. "Unless people tend to look upon drinking water as an economic resource which they have to pay for, it will not be economically and rationally used."
The government also plans to incorporate features such as rainwater harvesting in new water systems wherever possible.
In doing this, the government is taking a cue from a countrywide network of civic groups helping villages design and build low-technology traditional water systems.
One such place is the Alwar district in the desert state of Rajasthan.
Prithvi Raj Singh is with the group Jal Baradari or Water Community. He says in the past decade, villagers in Alwar built hundreds of structures to divert rainwater into the ground instead of letting it run off. The result was dramatic - turning an area short of water into one rich with water. In some cases, where people once had to dig wells hundreds of meters deep, they now have to go down only five or 10 meters.
"The groundwater recharge resulted and the river started flowing throughout the year …. So there was a tremendous impact. The vegetation is different, every village will be full of trees, the forests were rejuvenated," he said.
But such solutions are only part of the answer to India's colossal water problems. There is wide debate on how to encourage conservation of a resource that is fast running out. However, conservationists insist water is turning scarce only because it is not being managed properly, and simple methods such as catching the raindrops can help end the crisis.